JPH06181406A - Array antenna - Google Patents

Abstract

PURPOSE:To provide two zero points at positions symmetrical with respect to a major beam in the directivity characteristic of the antenna and to simplify the control of the antenna. CONSTITUTION:A weighting circuit 8 in existence between one port of a power distribution circuit 1 and four antenna elements 6-0, 6-1, 6-N, 6-(N+1) at its end has 1st and 2nd 1-input 2-output power distributers 9, 10, 11 of equal amplitude and phase and a 1st and 2nd gain variable devices 12, 13 whose gain is controlled by a control means 14, the 1st gain variable device 12 is connected between one port of the power distribution circuit 1 and an input of the 1st power distributer 9, and the 2nd gain variable device 13 is connected between a 2nd output of the 1st power distributer 9 and an input of the 3rd power distributer 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the directivity of an array antenna, and more particularly to an array antenna which combines two zero points.

[0002]

2. Description of the Related Art In order to synthesize two zero points in the directivity of an array antenna, for example, Inagaki, 1988 Transactions of the Institute of Electronics, Information and Communication Engineers B vol.J71-B No.9 pp.1044-1052, "Direction As described in "Zero point synthesis based on the principle of the product of sex", it is sufficient to control the element weights (amplitude and phase) of the four elements at the array end, and the zero point formation position can be controlled only by controlling the element weights. Can be controlled.

FIG. 5 shows an example of a case where an array antenna of this type is constructed by the conventional technique.

In the figure, for simplification of description, an array antenna arrayed in one dimension is shown.

In the figure, reference numeral 1 is a power distribution circuit for distributing one input signal (N + 2) with equal amplitude and same phase, 2-0,
2-1, 2-N, 2- (N + 1) are variable phase shifters, 3-
2, ..., 3- (N-1) are fixed phase shifters, 4-0, 4-
1, 4-N, 4- (N + 1) are gain changers, 5-2,
..., 5- (N-1) is a gain adjuster, 6-0, ..., 6-
(N + 1) is an antenna element, 7 is a variable phase shifter 2-0, 2
-1,2-N, 2- (N + 1) and gain changer 4-0,
It is a control means for controlling the 4-1, 4-N, 4- (N + 1).

Next, the operation will be described. According to the Inagaki paper, the excitation weight B _n (n = 0,
, N + 1) is set according to the following equations (1) to (5), two zero points can be combined.

[0007]

[Equation 1] _{Here, I n (n = 0,} ..., N-1) is the element weight of linear array of N elements, u ₁ and u ₂ are the antenna element spacing d, the wavelength lambda, the zero point forming position theta ₁ And θ ₂ are defined by the equation (6).

[0008]

[Equation 2] In the equation (7), f ₀ (u) is the directivity due to the element weight I _n (n = 0, ..., N−1) of the linear array consisting of N elements.

Array end 4 represented by the equations (2) to (5)
The element weight of the element is a general expression in the case where the zero point forming positions θ ₁ and θ ₂ form a zero point at an arbitrary position of directivity,
Now θ ₁ and θ ₂ are symmetric with respect to the main beam, that is, θ ₂ = −
(from equation _{(6), u 2 = -u 1) θ} 1 Considering the case of synthesizing the position of, (2) to (5) element weight of the array end 4 element of the formula is the following formula Give it.

[0010]

[Equation 3] The directivity at this time is expressed by Expression (12) from Expression (7).

[0011]

[Equation 4]

From the equation (13), the total directivity f (u) is
Element weight I _{n of a} linear array consisting of N isotropic elements
Original directivity f ₀ (u) according to (n = 0, ..., N−1)
And the directivity f ₁ (u) obtained by changing the weight of the element at the array end.

Therefore, the power distribution circuit 1 causes (N +
2) Among the distributed signals, antenna elements 6-2, ..., 6
-(N-1) is fed to the fixed phase shifters 3-2, ...,
3- (N-1) and gain adjusters 5-2, ..., 5- (N-
By 1), the element weight B _n (n = 2, ..., N-1) is adjusted, and the array end elements 6-0, 6-1, 6-N, 6-
The control unit 7 controls the variable phase shifters 2-0, 2 so that the signals fed to (N + 1) have the element weights B ₀ , B ₁ , B _N , and B _{N + 1} so that a zero point is formed at a desired position. -1,2-
N, 2- (N + 1) and gain changers 4-0,4-1,4
-N, 4- (N + 1) is adjusted and power is supplied to the antenna end elements 6-0, 6-1, 6-N, 6- (N + 1), respectively. In this way, the excitation weight _Bn (n =
By adjusting 0, ..., N + 1), the zero point can be combined at the position of ± θ ₁ .

Further, the zero point forming position ± θ ₁ can be controlled by controlling the excitation weights of the four elements at the array end so as to satisfy the expressions (8) to (11).

[0015]

Since the conventional array antenna is constructed as shown in FIG. 5, the zero forming position θ ₁ ,
When changing θ ₂ , it is necessary to control the excitation weight of the array end element while maintaining the relationships of equations (2) to (5). Further, even in the case of θ ₂ = −θ ₁ , it is necessary to control the excitation weight of the array end element while maintaining the relationships of the expressions (8) to (11).

In the conventional configuration, the variable phase shifters 2-0, 2-1 and
2-N, 2- (N + 1) and gain changers 4-0, 4-
The phase and amplitude are controlled at a total of 8 locations of 1,4-N and 4- (N + 1). Therefore, in the conventional configuration, the array end element 6-
In order to keep the signals feeding 0, 6-1, 6-N, 6- (N + 1) in the relationship of equations (2) to (5) or equations (8) to (11), the control means Variable phase shifter 2-
0,2-1,2-N, 2- (N + 1) and gain variable device 4
It is necessary to simultaneously control the phase and the amplitude at a total of 8 places of −0, 4-1, 4-N, 4- (N + 1). Therefore, there is a problem that the control system becomes large and the control method becomes complicated.

The present invention has been made to solve the above problems, and the positions of two zero points which are combined on the array antenna directivity by a simple control are symmetrical with respect to the main beam. The purpose is to obtain an array antenna controlled to (± θ ₁ ).

[0018]

The features of the present invention for achieving the above object are to realize a desired antenna directivity by controlling the excitation amplitude phase of each antenna element between a plurality of antenna elements and a power distribution circuit. In the array antenna, the weighting circuit is provided between one port of the power distribution circuit and the four antenna elements at the end, and the other antenna element is connected to the other port directly or via the amplitude / phase adjusting means,
The weighting circuit has first, second, and third 1-input 2-output power dividers of equal amplitude and in-phase, and first and second gain variable devices whose gains are controlled by the control means. The first gain variable device is connected between the one port of the power distribution circuit and the input of the first power distribution device, and the second gain variable device is connected to the second power distribution circuit of the first power distribution device. Output and third
Connected between the inputs of the first power distributor, the first output of the first power distributor is connected to the input of the second power distributor, and the two outputs of the second power distributor are connected to the antenna element. The two outputs of the third power distributor are connected to the two end elements, and the two outputs of the third power distributor are connected to the two antenna elements adjacent to the end elements, respectively.
It is in an array antenna that realizes a zero point in two angular directions.

A receiving antenna can be obtained by replacing the power distributor with a power combiner.

When the antenna elements are arranged two-dimensionally, a two-dimensional array antenna can be constructed by arranging a plurality of the one-dimensional array antennas having the above-mentioned configuration in parallel.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an embodiment of the present invention, and is a diagram showing an array antenna in which (N + 2) antenna elements are arranged one-dimensionally for simplification of description.

In the figure, 1 is a power distribution circuit for distributing one input signal to (N-1) output terminals with equal amplitude and same phase,
3-2, ..., 3- (N-1) are fixed phase shifters, 5-2,
..., 5- (N-1) is a gain adjuster, 6-0, 6-1,
, 6- (N + 1) is an antenna element, 8 is a weighting circuit, 9 is a first equal amplitude / in-phase power distributor, 10 is a second equal amplitude / in-phase power distributor, 11 is a third equal amplitude / In-phase power distributor, 12 is a first gain variable device, 13 is a second gain variable device, and 14 is a control means for controlling the gains of the first gain variable device and the second gain variable device.

In the description, it is assumed that there is no phase shift in the first and second gain varying devices and the first, second and third equal amplitude / in-phase power dividers for simplification of description. .

Let each output signal of the power distribution circuit 1 which distributes the input signal to the (N-1) output terminal be I ₀ . When it is desired to synthesize a zero point at a specific position of the original directivity f ₀ (u),
The original directivity f ₀ (u) is obtained by the one that feeds the antenna elements 6-2, ..., 6- (N-1) among the signals N-1 distributed by the power distribution circuit 1. Fixed phase shifter 3
-2, ..., 3- (N-1) and gain adjusters 5-2 ,.
Adjusting 5- (N-1), antenna elements 6-2, ..., 6
-Exciting (N-1). Further, among the signals distributed by the power distribution circuit 1, the signal input to the weighting circuit 8 is multiplied by G _{1 in the} amplitude amount by the first gain variable unit 12 to obtain the first equal amplitude / common mode power. The distributor 9 divides into two with equal amplitude and same phase. One of the two divided signals is connected to the second equal-amplitude / in-phase power divider 10, and the equal-amplitude / in-phase 2
To be distributed. Further, the other of the signals divided into two by the first equal amplitude / in-phase power distributor 9 is multiplied by G _{2 in} amplitude amount by the second gain variable device 13, and the third equal amplitude / in-phase power distributor is divided. It is divided into two with equal amplitude and in-phase by the device 11. That is, the signal input to the weighting circuit 8 is divided into four, and its four output terminals a, b, c and d (the second equal amplitude / in-phase power divider 1
Two output terminals of 0 are a and b, and two output terminals of the third equal amplitude / in-phase power distributor 11 are c and d. The signals A, B, C, and D in () are signals as in equation (14).

[0025]

[Equation 5]

Here, G ₁ and G ₂ represent the gains set by the two gain changers 12 and 13 in the weighting circuit 8, respectively.

In a one-dimensional array antenna, it is general to add excitation weights which are line-symmetric with respect to the center of the array such as equal amplitude excitation and Taylor distribution excitation for lowering side lobes to each element. At this time, (8) to (1
In the equation (1), I _N-1 is equal to I _0, and I _N-2 is equal to I ₁ . Therefore, in this case, B ₀ and B _{N + 1} , B
₁ and B _N are equal to each other.

In addition to equal-amplitude excitation, the excitation weight to be attached to each adjacent element is added to each element even when the excitation weight which is line-symmetric with respect to the center of the array such as Taylor distribution excitation for lowering the side lobe is added to each element. Changes smoothly, so that I ₀ and I ₁ can be approximated as equal. At this time, equations (8) to (11) are represented by the following equations.

[0029]

[Equation 6] Then, the equation (14) matches the equations (15) and (16).

Therefore, by feeding this signal to the array elements 6-0, 6-1, 6-N, 6- (N + 1) as shown in FIG. 1, the directivity f (u) obtained by combining the zero points is obtained. Obtainable. Further, the zero point forming position ± θ ₁ can be controlled by changing G ₁ and G ₂ of the four signals in the equation (14).

FIG. 2 shows the gains G ₁ and G ₂ of the first and second gain changers 12 and 13 in the weighting circuit 8 and the zero point forming position ± θ ₁ when the antenna element spacing d is 0.5λ. Shows the relationship.

From this figure, it is understood that the zero-point synthesis position can be varied by simply changing the gains of the first and second gain varying devices 12 and 13 in the weighting circuit 8.

Since the four signals fed to the four elements at the array end represented by the equations (15) and (16) can be changed only by the two gain changers 12 and 13 in the weighting circuit 8, the antenna is changed. The control means 14 for changing the excitation weight for synthesizing the zero point at the symmetrical position with respect to the directional main beam becomes simple, and the control method becomes simple.

Although the array antennas arranged in one dimension have been described above, the same can be explained for the array antennas arranged in two dimensions by arranging a plurality of the one-dimensional arrays in parallel. .

FIG. 3 is a diagram showing another embodiment of the array antenna according to the present invention. For simplification of description, (N + 2).
The antenna elements are arranged one-dimensionally, and the original directivity f _{0 is obtained.}
It is a figure shown as an array antenna in the case of uniform excitation directivity which excited each antenna element as (u) with equal amplitude and the same phase.

In the figure, 1 is a power distributor for distributing one input signal to (N-1) output terminals with equal amplitude and same phase, 6
-0, 6-1, ..., 6- (N + 1) is an antenna element, 8
Is a weighting circuit, 9 is a first equal amplitude / in-phase power divider,
10 is a second equal-amplitude / in-phase power divider, 11 is a third equal-amplitude / in-phase power divider, 12 is a first gain variable device, 12
-1 is a first amplification element, 12-2 is a first attenuator, 13
Is a second gain variable device, 13-1 is a second amplification element, 13
-2 is the second attenuator, 14 is the first and second attenuators 12
It is a control means for controlling the attenuation amounts of −2 and 13-2.

The operation of the embodiment of the present invention shown in FIG. 3 will be described. In the present embodiment, since the original directivity f ₀ (u) is the case of uniform excitation directivity in which each antenna element is excited with the same amplitude and the same phase, the antenna element 6-
The signals obtained by the power distribution circuit 1 can be directly used for 2, ..., 6- (N-1).

Let I _{0 be} each output signal of the power distribution circuit 1 that distributes the input signal to the (N-1) output terminals with equal amplitude and same phase.

In the power distribution circuit 1, with the same amplitude and the same phase (N-
1) Of the distributed signals, (N-2) signals I ₀ are fed as they are as excitation weights of the antenna elements 6-2, ..., 6- (N-1). Further, the remaining one signal I ₀ distributed by the power distribution circuit 1 is divided into four signals by the weighting circuit 8 into the signal of the formula (14), and the array end element 6 is formed.
Power is supplied to −0, 6-1, 6-N, 6- (N + 1).

That is, G ₁ I is added to 6-0, 6- (N + 1).
_0/2, the 6-1,6-N feeding the G ₁ G ₂ I _0/2. As a result, the directivity f (u) is obtained by combining two zero points that are symmetrical with respect to the main beam on the original uniform excitation directivity f ₀ (u).

Further, the control means 14 controls the first and second attenuators 12-2 and 12-2 in the first and second gain changers 12 and 13, respectively.
By controlling the attenuation amount of 13-2, the zero signal forming position (± θ ₁ ) is controlled by changing G ₁ and G ₂ of the four signals shown in the equation (14) as shown in FIG. be able to.

FIG. 4 shows an array antenna according to the present invention, in which the number of antenna elements N = 20 and the spacing between the antenna elements d =
FIG. 6 is a diagram showing an example in which zero points are combined at a position of 0.5λ and uniform excitation directivity θ ₁ = ± 40 °. In the figure, the solid line shows the directivity in the case of zero-point synthesis, and the dotted line shows the original uniform excitation directivity.

In the above-mentioned embodiment, the one-dimensional array antenna is described, but the same applies to the two-dimensional array antenna by arranging a plurality of the one-dimensional arrays in parallel. Can be explained.

Further, when the excitation weight is set for each antenna element such as Taylor directivity as the original directivity f ₀ (u), as shown in FIG. 1, the power distribution circuit 1 and the antenna element 6-
A fixed phase shifter and a gain adjuster may be inserted between 2, ..., 6- (N-1) to perform excitation weighting.

It should be noted that although the above description mainly deals with the transmitting antenna, it goes without saying that it is also applicable to the receiving antenna.

[0046]

As described above, according to the present invention, the excitation weights of the four elements at both ends of the array antenna are changed only by controlling the gains of the two gain varying devices in the weighting circuit, and the formation position of the zero point is changed. Since they can be controlled, there is an effect that the formation positions of two zero points that are symmetrical with respect to the main beam in the antenna directivity can be controlled with a simple control system configuration and a simple control method. Therefore, the side lobe can be suppressed, or, if there is an interference wave in a specific direction, the antenna sensitivity in that direction can be set to zero.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a gain of a gain varying device in a weighting circuit and a zero-point combining position when an antenna element interval d = 0.5λ.

FIG. 3 is a configuration diagram showing an embodiment of an array antenna of the present invention.

FIG. 4 is a diagram showing an embodiment of the array antenna of the present invention in FIG. 3, in which the number of antenna elements N = 20 and the antenna element spacing d =
FIG. 6 is a diagram showing a uniform excitation directivity when 0.5λ and a directivity when the zero point composition is performed at a position of ± 40 ° of the uniform excitation directivity.

FIG. 5 is a configuration diagram of a conventional array antenna.

[Explanation of symbols]

1 power distribution circuit 2-0,2-1,2-N, 2- (N + 1) variable phase shifter 3-2, ..., 3- (N-1) fixed phase shifter 4-0,4-1,4- N, 4- (N + 1) gain changer 5-2, ..., 5- (N-1) gain adjuster 6-0,6-1, ..., 6- (N + 1) antenna element 7 variable phaser 2-0 , 2-1, 2-N, 2- (N +
1) and gain changers 4-0, 4-1, 4-N, 4- (N
+1) Controlling means 8 Weighting circuit 9 First equal amplitude / in-phase power distributor 10 Second equal amplitude / in-phase power distributor 11 Third equal amplitude / in-phase power distributor 12 First gain variable device 12-1 1st amplification element 12-2 1st attenuator 13 2nd gain variable device 13-1 2nd amplification element 13-2 2nd attenuator 14 1st gain variable device and 2nd Control means for controlling the gain of the gain adjuster

Claims (2)

[Claims] 1. An array antenna for realizing a desired antenna directivity by controlling an excitation amplitude phase of each antenna element between a plurality of antenna elements and a power distribution circuit, wherein one port of the power distribution circuit and four of the end portions are provided. A weighting circuit is provided between the antenna element and one antenna element, and the other antenna element is connected to another port directly or through amplitude / phase adjusting means. A power distributor having equal amplitude and same phase of outputs, and first and second gain variable devices whose gains are controlled by the control means, wherein the first gain variable device is the one of the power distribution circuits. A second gain adjuster connected between the second output of the first power divider and an input of the third power divider; The first output of the one power divider is the second output Connected to the input of the power distributor, the two outputs of the second power distributor connected to the two end elements of the antenna element, and the two outputs of the third power distributor each adjacent the end element. An array antenna, which is connected to two antenna elements, and realizes zero points in two angular directions on the antenna directivity characteristics by controlling a gain variable device. 2. An array antenna for realizing desired antenna directivity by controlling the excitation amplitude phase of each antenna element between a plurality of antenna elements and a power combining circuit, wherein one port of the power combining circuit and 4 A weighting circuit is provided between the antenna element and one antenna element, and the other antenna element is connected to another port directly or via an amplitude / phase adjusting means. The power combiner having the same amplitude and the same phase of the outputs, and the first and second gain varying devices whose gains are controlled by the control means, the first gain varying device is the one of the power combining circuits. A second gain variator connected between the second input of the first power combiner and an output of the third power combiner; The first input of the power combiner of 1 is the second input of Connected to the output of the power combiner, the two inputs of the second power combiner are connected to the two end elements of the antenna element, and the two inputs of the third power combiner are each adjacent to the end element. An array antenna, which is connected to two antenna elements, and realizes zero points in two angular directions on the antenna directivity characteristics by controlling a gain variable device.